A man has been jailed for a minimum of 25 years after carrying out a sexual assault on his 64-year-old mother-in-law that led to her death.

Mohammed Yassin Yusuf, 32, sexually assaulted Amoe Seline Stevens so violently she later died of her injuries.

The Old Bailey heard how Yusuf's wife had left him at home with her "frail" mother, Mrs Stevens at the address they shared in Cairnfield Avenue, Dollis Hill on October 18 last year.

The pensioner had suffered a stroke in the past and as a result her mobility and speech had been severely impaired.

Within moments of being left alone, Yusuf had locked himself in his mother-in-law's bedroom and started to assault her.

The assault only ended when a registered carer arrived to get Mrs Stevens ready for bed.

The carer became suspicious as Yusuf rushed from the bedroom to the kitchen with blood spots on his hands and shirt.

When she entered the bedroom she saw Mrs Stevens slumped in a recliner chair with blood smeared across her legs and a pool of blood on the floor.

Mrs Stevens was taken by ambulance to St Mary's Hospital in Paddington but died from her injuries within hours. A post-mortem examination revealed that she had haemorrhaged after suffering multiple internal injuries.

Yusuf was arrested and subsequently charged with murder the following day. He was found guilty at the Old Bailey on June 2, and was jailed for life at the same court today.

Detective Chief Inspector Noel McHugh of the Homicide and Major Crime Command, who led the investigation, said: "This was a truly horrendous crime committed against a vulnerable and defenceless woman and today's sentence reflects that.

"Mrs Stevens suffered ill health and Yusuf should have offered her care and protection. Instead he chose to use her vulnerabilities to his own sexual benefit and violated her in the most despicable way possible.

"We believe Yusuf had assaulted Mrs Stevens on multiple occasions but due to her disabilities she was never able to communicate with her family and expose his sickening actions. We also believe that Yusuf is sexually deviant and may well have tried to target other women in his past.

"We would urge anyone who came into contact with Yusuf and had concerns about his behaviour to come forward and contact our Incident Room on 020 8785 8099."

The family of Amoe Stevens said in a written statement: "My family will never recover from the way in which our beloved mother was taken from us."